If you’ve ever thought about tinkering with your Android device, you’ve probably read that you need to flash a custom recovery onto it before you can do anything serious. But, that begs a few questions — what’s a recovery? What’s a custom recovery? What are my options for custom recoveries? We’re going to take a complete look at recoveries so that you can be well-informed when you start messing with your Android device.

What’s a Recovery?

An Android device consists of several pieces of software, which include the bootloader, radio, recovery, and system. The bootloader is the first piece of software that is run when your device turns on — it decides whether to load the recovery, or load Android (“system”) and the radio. The radio is simply the controller for your antennas, which give you a cellular connection to your carrier’s towers, but the radio is pretty irrelevant for the purposes of this article.

The recovery, simply put, is a runtime environment (think “mini operating system”) separate from Android that can perform various system-related tasks. The stock recovery on most Android devices can apply OTA (over-the-air) updates, delete user and cache content (for factory reset purposes), and allow external tools from a microSD card to run functions on the device.

Compared to a full-sized PC, it is most similar to the BIOS in that it is a small piece of software that is independent of the operating system and can control various system settings and functions, but it does not actually perform the same exact tasks. For example, the recovery doesn’t control any I/O functions, which is entirely what the BIOS is about. The recovery also has no power as soon as Android is being loaded.

And a Custom Recovery?

A custom recovery is a non-stock recovery, which people can install over the stock recovery. There are many different reasons why someone will want to install a custom recovery — most of those reasons are extra functionality. Most of the major features include:

The ability for third-party ROMs to be installed over the stock Android image

The ability to perform Nandroid backups — these are very good backups that saves literally everything from your personal data to the operating system itself

The ability to communicate with the Android Debug Bridge, or adb, on a computer for debugging and other developer-type actions, which is otherwise only possible when enabling developer tools within Android

A more useful and/or visually-pleasing interface for the recovery, which can include touch capabilities or an interface not driven by menu options.

Long story short, custom recoveries allow you to do various things that the manufacturer may not want you to do with it. They make the stock recovery so limited for the sake of making sure that you don’t turn your device into a brick, but you know what you’re doing, right?

CWM and TWRP

The top two most popular custom recoveries are ClockworkMod (CWM) [No Longer Available] and Team Win Recovery Project (TWRP). Both of these recoveries are fantastic choices and come loaded with features (including the ones I listed above).

CWM has been the recommended recovery for a long time and is still the most-used one, but TWRP has been gaining more popularity, has a few more options, and is even themeable. CWM is menu-driven and comes with a boring interface, but it works well.

TWRP is more dynamic as it displays large buttons that you can easily tap on to execute, and it also guesses what you’ll want to do next: The buttons aren’t set in stone. For example, after flashing a new ROM, it’ll replace one of the buttons with an option to wipe the cache and other related functions. It also stays in the folder you browsed to last, which is great if you have multiple related files you need to flash that are all located in the same folder. Both projects boast a long list of supported devices, so you should be able to find a recovery made for your device.

Other Custom Recoveries

If you’re curious about recoveries other than CWM and TWRP, you should definitely check out the XDA-Developers forum for more recoveries that support your device. Search by going to your device’s subforum and looking for threads with a [Recovery] tag on them. All recoveries should address the main points that a custom recovery provides, but they can vary on how they tackle those points. The most obvious change between them will be their different interfaces.